In a small saucepan over medium heat, combine sugar, lemon juice, orange juice, salt and egg yolks. Stir constantly with a whisk for about 6 minutes until mixture is thick; remove from heat.
Add butter and lemon zest and continue to stir until butter is melted. Pour the mixture into a bowl, cover with plastic wrap and place in the fridge until cooled completely.
Once chilled, spoon 2 tablespoons of curd into 8 small cups (or 2 large dishes if so desired), followed by a layer of blueberries and raspberries. Repeat these layers and top with granola, berries and a tiny sprig of mint. Enjoy!